The Metabolic Pathophysiology Core Laboratory will take advantage of the very strong metabolic research program at Vanderbilt to provide a core laboratory to study metabolism. The core will be divided into two subcores: Metabolic Regulation In Vivo and Tissue and In Vivo Imaging. The Metabolic Regulation In Vivo Subcore will provide tools to accurately assess metabolism in healthy, conscious, non-stressed mice in a cost-effective and efficient manner, while ensuring animal welfare. It will be housed in a newly skills in chronically implanting catheters into the carotid artery and jugular vein to study metabolism in conscious mice. In addition the core will provide services to assess energy balance and expenditure, and voluntary feeding and activity behavior. This core will provide not only standardized tests for metabolic and endocrine assessments but also give advice to users on more sophisticated procedures that could be done in collaboration with other investigators with a given expertise. The Tissue and in Vivo Imaging Laboratory Subcore will offer novel imaging technology. The two imaging resources are: 1) a multi-photon excitation confocal microscope with which investigators can visualize real time kinetics of calcium, NAD(P)H, pH as well as fluorescent probes in freshly isolated cells and in situ whole organ preparations (liver, pancreas, muscle brain) and 2) Optically image the real-time kinetics of gene expression in intact animals by combining luciferase as a reporter gene with a state-of-the-art highly sensitive optical single photon detection system. This Core by virtue of its novel subcores will provide stat of the art technology to delineate the mechanism for the phenotypic expression of metabolic disorders in mice.